Characterization of talc deposits in ultramafic rocks of Gebel El Maiyit and its economic feasibility

Our plain-English summary of Characterization of talc deposits in ultramafic rocks of Gebel El Maiyit and its economic feasibility, by I.A. Salem, S.M. Aly, A. Shebl, et al (Scientific Reports, 2025).

The study

• Authors: I.A. Salem, S.M. Aly, A. Shebl, I.A. Thabet
• Journal: Scientific Reports
• Published: 2025;15(1):14361
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

A comprehensive, multiscale investigation, integrating remote sensing, mineralogy, whole rock chemistry, Electron Microprobe (EMP), and stable isotopes (oxygen-18O and carbon-13C), was undertaken to assess the feasibility of talc deposits and their host serpentinite at Gebel El-Maiyit in the Eastern Desert of Egypt. Sentinel 2 remote sensing images were applied to discriminate talc from serpentinites followed by geochemical study of serpentinites using RO`/SiO2 ratios, AFM diagram and MgO versus SiO2 relationship indicates a peridotite origin formed at low temperature Alpine type. Our study revealed that talc deposit has a varied mineralogical composition and according to the predominant talc and gangue minerals three main types have been distinguished: 1- pure talc, 2- tremolite talc and 3- chlorite talc. Paragenetically, talc is derived from serpentine minerals, tremolite and chlorite. The latter is formed at about 231 °C. The chemical data of talc deposit reveals that the summation of talc components (SiO2 + MgO + H2O) is 92.68%, while that of impurity oxides (Al2O3 + CaO + Fe2O3 + FeO) is 5.56%. The carbon13C) and oxygen18O) contents of pure magnesite revealed that the pure phase of Gebel El-Maiyit was formed at low temperature (around 100 °C) while magnesite contained in talc carbonate rock was formed at high temperature (140-175 °C). In terms of source fluids, the metamorphic and /or magmatic water was supposed to be the main fluids which are circulated during the hydrothermal alteration. Although S and P are very minor components in all the talc ore types of the considered area and do not affect their industrial use. Copper (Cu) was not detected. Iron (Fe) and manganese (Mn) concentrations are significantly high, necessitating treatment to reduce these elements for the ore to be suitable as an electrical insulator. Arsenic (As) levels are consistently below 5 ppm, indicating the ore's potential use in the cosmetic industry without further processing.

© 2025. The Author(s).

In plain English

This was a geological study of talc deposits in serpentinite at Gebel El-Maiyit in the central Eastern Desert of Egypt. It did not examine human exposure or health. The authors mapped talc-carbonate rock separately from its host serpentinite using Sentinel 2 images sharpened with higher-resolution PRISM data. They analyzed subsets of more than thirty collected samples: 22 by X-ray diffraction, six by thermal analysis, four by carbon and oxygen isotopes. Host-rock serpentine minerals were antigorite, lizardite and chrysotile. They described three talc ore types: pure talc (90% or more talc, with less than 10% chlorite and tremolite), tremolite-talc, and chlorite-talc, in which chlorite and talc were nearly equal and tremolite and chrysotile were also detected. Chrysotile formed small veinlets in the chlorite-talc ore; tremolite-talc ore was sometimes fibrous. Talc components made up 92.68% of the ore and impurity oxides 5.56%. The authors concluded that iron and manganese were high enough to need treatment before use as an electrical insulator. Because arsenic was always below 5 ppm, they concluded the ore could be used in cosmetics without treatment.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Geological field and laboratory study of a talc deposit (satellite remote sensing, petrography, X-ray diffraction, whole-rock chemistry, electron microprobe, thermal analysis, stable isotopes); no human subjects
• Who was studied: More than thirty rock samples were collected from the Gebel El-Maiyit serpentinite body, central Eastern Desert, Egypt. Analyses used subsets: X-ray diffraction on 10 serpentinite, 3 talc-carbonate and 9 talc ore samples; chemical analysis on 13 serpentinite and talc-carbonate samples and 9 talc ore samples; microprobe on more than ten samples; thermal analysis on 6; isotopes on 4 carbonate-rich samples.
• Exposure: No human exposure was studied. The minerals characterized in the talc ore were talc, tremolite, chlorite, chrysotile, antigorite and chromite; actinolite was also identified.
• Main results:
  • Three serpentine minerals were recognized in the host serpentinite: antigorite, lizardite and chrysotile.
  • Pure talc ore was 90% or more talc, with minor chlorite and tremolite making up less than 10%.
  • Chlorite-talc ore contained chlorite and talc in nearly equal proportions, with tremolite and chrysotile also detected.
  • In the chlorite-talc ore type, chrysotile occurred as small veinlets cutting across the talc and chlorite.
  • The tremolite-talc ore type was described as sometimes fibrous and schistose.
  • Across the talc ore samples, talc components (SiO2 + MgO + H2O) summed to 92.68% (printed as 92.685 in the body text, 92.68% in the abstract). Impurity oxides summed to 5.56%.
  • The sum of talc components fell from 94.19% in pure talc ore to 91.76% in tremolite-talc ore and 82.97% in chlorite-talc ore.
  • Iron and manganese contents of the ore were considerably high, and copper was not detected.
  • Chlorite formation temperature was estimated at 164 to 251 °C, with an average of 231 °C.
  • Pure magnesite formed at around 100 °C; magnesite in talc-carbonate rock formed at 140 to 175 °C.
  • Images from PRISM pan-sharpened Sentinel 2 combinations (2.5 m) showed the talc-carbonate rocks mainly along the borders of the serpentinite body.
• The authors' conclusion: The authors concluded that the ore needs treatment to reduce iron and manganese before use as an electrical insulator. Because arsenic was always below 5 ppm, they concluded the ore could be used in the cosmetic industry without treatment.

Topics

Medical terms in this study, explained in our Lexicon: Talc, Ultramafic Rocks, Mineralogy, Electron Microprobe Analysis, Serpentinite, Peridotite, Tremolite, Chlorite.

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• Bioleaching of ultramafic tailings by acidithiobacillus spp. for CO2 sequestration — I.M. Power, G.M. Dipple, et al. (2010)
• Occurrence, behaviour, and human exposure pathways and health risks of toxic geogenic contaminants in serpentinitic ultramafic geological environments (SUGEs): A medical geology perspective — W. Gwenzi (2020)
• Experimental asbestosis. The development of lung cancer in rats with pulmonary deposits of chrysotile asbestos dust — P. Gross, R.T. DeTreville, et al. (1967)

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